Search PubMed⌕ Search

Biomedical subjects

C Martín

Publications and source records attributed to C Martín.

At least 19 recordsLinked to original sources
PubMed1995

Protective effect of estrogens and catecholestrogens against peroxidative membrane damage in vitro.

The antioxidant effects of natural estrogens (estrone, E1; 17 beta-estradiol), synthetic estrogens (17 alpha-ethynylestradiol, EE2; mestranol, MES; diethylstilbestrol, DES) and catecholestrogens (2-hydroxyestradiol; 4-hydroxyestradiol, 4-OHE2) on lipid peroxidation induced by different means in rat liver microsomes were investigated. The extent of lipid peroxidation was determined by measuring thiobarbituric acid reactive substances. Prooxidants included Fe3+/ADP/reduced NADPH, Fe2+/ascorbate, tert-butyl hydroperoxide (t-BOOH) and 2,2'-azobis(2-amidinopropane) (AAPH). Estrogens and catecholestrogens decreased lipid peroxidation in all four systems tested. In the iron/ascorbate model it was shown that (i) 4-OHE2 and DES had analogous patterns of inhibition, irrespective of the presence of NADPH or the functional integrity of the microsomes, and (ii) the antioxidant activities of E1, EE2 and MES were dependent on the assay conditions with the activity being markedly higher when estrogen metabolism was favored. When peroxidation was initiated by the peroxyl radical generator AAPH, the inhibitory effects observed were least pronounced. Our data also showed that, in each of the systems, all inhibitors displayed the same order of inhibitory potency with DES and catecholestrogens being the most potent antioxidants under all experimental conditions used. The present results confirm earlier findings and point toward a link between estrogen metabolism and estrogen antioxidant activity. The data also indicate that estrogens and catecholestrogens interact with the peroxidative process at different levels with their interactions with iron or the metal-derived species being the most important modes of inhibition.

Animals↗
PubMed1995

Effect of body position on gas exchange in patients with unilateral pleural effusion: influence of effusion volume.

The objective of this study was to evaluate the effect of lateral body position on gas exchange in patients with unilateral pleural effusion, with special reference to the influence of effusion volume. Thirty consecutive patients with unilateral pleural effusion, without evidence of parenchymal pulmonary involvement, were entered into the study. Arterial blood gas tensions (PaO2, PaCO2) were randomly measured in both right and left lateral decubitus body positions, while breathing room air. To assess the influence of the effusion volume, roentgenographic and functional parameters were used. Among the latter, FVC, FEV1, TLC and RV were determined. The influence of the presence or absence of pleuritic pain on gas exchange was also assessed. There was no significant difference in PaCO2 between right and left lateral decubitus body positions (31.1 +/- 4.2 vs. 31.0 +/- 4.5 mmHg). The differences in PaO2 between the two body positions ranged from 0.5-25 mmHg (mean 9.3 +/- 6.6 mmHg). Mean PaO2 with the normal-side (control) down (PaO2-N) (81.4 +/- 8.5 mmHg) was higher, but without significant statistical difference, than mean PaO2 with the effusion-side down (PaO2-E) (78.0 +/- 12.5 mmHg). PaO2-N was higher than PaO2-E in 22 of 30 patients (conventional), and lower in eight patients (paradoxical). No consistent relationship was found for alterations in PaO2 in different positions with the volume of effusion, either when estimated by a roentgenographic method or when using spirometric or plethysmographic values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Effects of TNF-alpha on the production of vasoactive substances by cerebral endothelial and smooth muscle cells in culture.

The effects of tumor necrosis factor-alpha (TNF-alpha) on the production of the vasoactive substances nitric oxide (NO) and endothelin-1 (ET-1) were investigated in cerebrovascular cells in culture. Bovine cerebral endothelial cells (BCEC) stained positively for NADPH-diaphorase/NO synthase activity and spontaneously produced nitrite, a stable NO oxidation product, which accumulated in the culture medium in a linear way for 48 h. Low concentrations of TNF-alpha (0.5-2 ng/ml) significantly enhanced nitrite production after a 24-h incubation. Higher concentrations or longer exposure times resulted in a cytotoxic effect that altered cell morphology, released lactate dehydrogenase (LDH) to the culture medium, and reduced the protein content. Dexamethasone, but not the NO synthase inhibitor N-iminoethyl-L-ornithine (L-NIO), prevented the cytotoxic effect of TNF-alpha in BCEC. TNF-alpha also significantly enhanced nitrite production in bovine cerebral smooth muscle cells (BCSMC). The enhancement was detected at all times between 8 and 72 h and at all concentrations tested (2-100 ng/ml). Signs of cytotoxicity were not observed in BCSMC after incubation with TNF-alpha. ET-1 was constitutively secreted by BCEC. The production of ET-1 was stimulated by thrombin. TNF-alpha enhanced the release of ET-1 in BCEC, and this enhancement was not modified by the simultaneous addition of interferon-gamma (IFN-gamma). BCSMC did not produce ET-1, either spontaneously or in the presence of TNF-alpha, IFN-gamma, or of both together.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Gene rearrangement in acute non-lymphoblastic leukaemia: correlation with morphological and immunophenotypic characteristics of blast cells.

The presence of Ig and TCR gene rearrangement has been reported to occur in ANLL. However, most of the studies have been performed in short series of patients and, in general, not all rearranging genes have been included. We have investigated the configuration of immunoglobulin (Ig) and T-cell receptor loci (TCR) in a series of 160 untreated patients with de novo acute non-lymphoblastic leukaemia (ANLL) and correlated the results with the morphological and immunophenotypic characteristics of blast cells. IGH gene rearrangement was detected in 16/160 cases analysed (10%) and IGK was rearranged in half of them. The incidence of cases displaying TCRB, TCRG and TCRD rearrangements was 5.6%, 13.8% and 13%, respectively. Concomitant recombinatorial events including different Ig and/or TCR genes were frequently detected. Gene rearrangement was not related to the stage of cell differentiation within the myeloid lineage assessed both by morphological and immunophenotypic criteria. Regarding the correlation with the presence of lymphoid related markers, the only relevant association was between the expression of CD7 antigen and TCRG and TCRD gene rearrangement. Our results show that the incidence of gene rearrangement in ANLL may be slightly higher than previously suspected, and that it is not associated with early stages of cell differentiation nor to the expression of lymphoid markers.

Antigens, CD↗
PubMed1995

[Nocardiosis in patients with human immunodeficiency virus infection in Spain].

BACKGROUND: Nocardia usually infects immunosuppressed patients, particularly with cellular immunity deficiency. Nevertheless, despite severe immunosuppression in patients infected with HIV, nocardiosis is rare among these patients. We report here two cases of nocardiosis in patients with HIV infection and review spanish literature up to 1993, with an analysis of the characteristics of this infection in our country. METHODS AND RESULTS: The two patients consumed drugs parenterally and Nocardia organism were recovered in blood cultures after 48 hours of inoculation in standard culture media. The source of the infection was cutaneous in one patient, over an area of venipuncture, and pulmonary in the other patient. Previously, eleven cases of nocardiosis had been reported in the spanish literature in patients infected with HIV. Eighty-four percent were males, and all of them consumed drugs parenterally and displayed a severe cellular immunodepression; the total CD4 lymphocyte count was lower than 100/mm3 in patients when this finding was available (6/13). At diagnosis only one patient received prophylaxis against other type of infection with antibiotics theoretically effective against Nocardia at diagnosis. The Nocardia species recovered more frequently was asteroides (77%) and the most common location was the skin (54%). Treatments more frequently employed were sulfametoxazole-trimethoprim (45%) and sulfadiazine (36%), with a good response except in those with cerebral involvement. CONCLUSIONS: Nocardiosis in patients with HIV infection is rare in Spain. In contrast with other geographical areas skin involvement was the more common form of infection. Prophylaxis with sulfametoxazole-trimethoprim against other infections could be responsible for a lower than expected incidence among this type of patients.

AIDS-Related Opportunistic Infections↗
PubMed1995

[Clinical experience with the treatment of metastatic renal cell carcinoma with subcutaneous interleukin-2r (IL-2r) and interferon Alpha-2b (IFN Alfa-2b)].

This work presents our recent clinic experience in the treatment of advanced RCC with IL-2 in association to alpha IFN given subcutaneously. Fifteen patient with histologically confirmed advanced RCC and measurable lesions were entered in the study. Patients were treated in cycles of 7 weeks at a IL-2 dose of 4.8 million IU/m2 (induction phase)-2.4 million IU/m2 (maintenance phase) every 12h five days a week and alpha IFN: 6 million IU/m2 every 24h three days a week, and were afterwards evaluated for response. Responders with localized residual bulk underwent rescue surgery. Seven patient has objective response (3 complete, 2 partial and 2 stable responses). The complete responses were stable and lasted 36 m, 14 m and 8 m, and global survival was of 14.6 m (3-36 m). All patients had toxicity at various degrees but WHO grade II was not exceeded at any time. The association of IL-2 and alpha IFN 2b given subcutaneously, appears to have antitumoral activity against advanced RCC with durable responses and in a proportion similar to other associations in intravenous administration, but with lower systemic toxicity. Surgical resection of residual bulk can be beneficial in selected patient with partial response.

Adult↗
PubMed1994

[Treatment of chronic hepatitis C virus infection with interferon in patients infected with the human immunodeficiency virus].

FOUNDATION: We assessed the effectivity of the treatment with interferon (IFN) in patients infected by the human immunodeficiency virus (HIV) with chronic hepatitis (CH) by the hepatitis C virus (HCV). METHODS: We studied 14 heterosexual males ex-parenterally drug consumers (PDC) and infected by the HIV (mean age 26 +/- 4.2 years), belonging to group A of CDC (1993); 10 had values of CD4 > 500 mmc and 4, between 200 and 500, the latter receiving treatment with zidovudine. In all these patients, the diagnosis of active chronic hepatitis was confirmed through histology. Three MUI of IFN-alpha 2b, 3 days/week during 24 weeks were administered. Sustained response to treatment was considered as the normalization of the aminotransferase levels until the end of the study; partial response, as the 50% decrease in the initial levels until the end of the treatment; relapse, as the response and latter increase in 1.5 of the ALT values at the end of the 24 weeks; and absence of response, as the lack of significant changes in the aminotransferase concentrations. RESULTS: Tolerance of the treatment was good, without severe side effects and just in one case, the medication had to be interrupted. In 5 patients, there was a response (all of them with more than 500 CD4). In 2 of these patients, the response was partial. In 3, there was a relapse and 3 other patients did not show any response (CD4 > 500). Three patients gave up the treatment. CONCLUSIONS: IFN-alpha 2b is well tolerated in a 24-week treatment in patients with HIV, CH and HCV. However, it was only effective for the control of this disease in patients with HIV infection with more than 500 lymphocytes CD4, without any significant effect in the evolution of the HIV infection.

HIV Infections↗
PubMed1994

[Nutrient content in raw and processed foods derived from cereals and legumes. I: Centesimal composition and energetic value].

Proximate composition and metabolizable energy of raw and processed foods derived from cereals and legumes, were determined. Results can be used to revise the out of day national composition table, to incorporate data of ash, new data of dietary fiber obtained by an enzimatic hydrolysis method, asimilable carbohydrates and metabolizable energy. They also replace the composition of various foods which were compiled from foreing tables. Difference observed on values of lipids in those foods with low lipid content, are imputed to the solvents used in the extraction.

Dietary Fiber↗
PubMed1992

Growth and morphogenesis in Streptomyces.

In this report we propose a model of apical growth for streptomycetes. The apical tip is considered as a multilayered wall that expands by an inside-to-outside mechanism of growth. It is also assumed that each layer is made up of peptidoglycan blocks, each of them being the result of the biosynthetic activity of a wall-synthesizing unit or membrane-associated growth zone. According to our model, apical growth occurs as follows: as a consequence of the hydrostatic pressure and the cleavage of some bonds, the layers are pushed and forced to slide (one with respect to the other), migrating from the center of the tip (at the inside of the wall) towards a peripheral location (at the outside of the wall). The model also incorporates a mechanism by which apical growth can be regulated and coordinated with the replication of the chromosome.

Cell Wall↗
PubMed1992

Temperature-sensitive mutants of the Mycobacterium plasmid pAL5000.

Two plasmids were isolated as thermosensitive replicons following in vitro mutagenesis of pB4, a pAL5000 derivative mycobacteria/Escherichia coli shuttle plasmid. Plasmids pCG59 and pCG63 replicate at 30 degrees C but not at 39 degrees C. This will allow their utilisation for transposon delivery, site-specific integration, or allele exchange.

Escherichia coli↗
PubMed1992

Nitric oxide mediates tumor necrosis factor-alpha cytotoxicity in endothelial cells.

Tumor necrosis factor alpha (TNF-alpha) exerts multiple actions on endothelial cells including among others the expression of pro-coagulant activity and adhesion molecules, and secretion of cytokines. We now show that TNF-alpha induces a time- and dose-dependent cytotoxic effect on cultured bovine aortic endothelial cells. This TNF-induced cytotoxicity, which is preceded by increased production of nitric oxide (NO), is significantly decreased by the NO synthase inhibitor N-iminoethyl-L-ornithine (L-NIO). Dexamethasone, which prevents the expression of cytokine-induced NO synthase in endothelial cells, also inhibits TNF-alpha-dependent cytotoxicity. The results indicate that NO is involved in the cytotoxic effect of TNF-alpha on endothelial cells.

Amino Acid Oxidoreductases↗
PubMed1992

[Acute organophosphate insecticide poisonings in the province of Almería. A study of 187 cases].

BACKGROUND: The aim of the present study was to analyze the epidemiological and clinical characteristics of poisoning by organophosphorus insecticides in the province of Almería. METHODS: One hundred eighty-seven patients diagnosed with organophosphorus insecticide poisoning were included from 1981-1986. In all the cases a previously established clinic and therapeutic protocol was applied. RESULTS: Eighty-six percent of the patients were males with a mean age of 31 years. The poisoning was accidental in 62% of the cases and attempted suicide in 38%. The via of absorption was cutaneous-respiratory in 57% and digestive in 43% of the patients. All the patients presented florid initial cholinergic symptomatology. The presence of bronchorrhea, tremor-fasciculations, respiratory depression and diminution in the level of conscience was associated with severe intoxication. The quantification of acetylcolinesterase was useful as a diagnostic parameter. Global mortality was 4%. Ten percent of the patients developed delayed signs of neurotoxicity. CONCLUSIONS: The high hospital demand for poisoning by organophosphorus insecticide is of note. Hospital mortality is low. The severity of intoxication is related with attempts of autolysis, digestive absorption, appearance of respiratory manifestations and of the central nervous system and the development of complications.

Acute Disease↗
PubMed1992

Analysis of the regions responsible for IS6110 RFLP in a single Mycobacterium tuberculosis strain.

A high degree of IS6110 restriction fragment length polymorphism (RFLP) is observed amongst the different strains of the Mycobacterium tuberculosis complex. The sequences of the IS6110 flanking regions from a M. tuberculosis strain harbouring four IS6110 copies were determined. Duplication of 3-4 nucleotides was found at the extremities of the four IS6110 copies, suggesting that IS6110 RFLP is due to transposition of the IS element. One of the copies of IS6110 analysed in the study was shown to be located at the same site in the genome of M. tuberculosis as the single copy present in an M. bovis BCG strain.

Base Sequence↗
PubMed1992

Isolation and analysis of IS6120, a new insertion sequence from Mycobacterium smegmatis.

Insertion sequence IS6120 from Mycobacterium smegmatis was identified by its ability to transpose into different sites in the lambda repressor gene, cl857, carried on an Escherichia coli/mycobacteria shuttle plasmid. IS6120 is a novel 1.5 kb insertion sequence, which has 24-bp imperfect terminal inverted repeats and generates 9-bp duplications of the target DNA following insertion. IS6120 is present in at least three copies in M. smegmatis but was not found in other species, including Mycobacterium tuberculosis. Nucleotide sequence analysis revealed that IS6120 contains two open reading frames, one of which encodes a putative transposase with similarities to those found in IS256 from Staphylococcus aureus, IST2 from Thiobacillus ferrooxidans, and ISRm3 from Rhizobium meliloti. The fact that IS6120 does not recognize a consensus target sequence for insertion and has no homologous sequences in the other strains studied makes IS6120 useful for transposon mutagenesis in mycobacteria.

Amino Acid Sequence↗